In Joomla 2.5 they upgraded the core SEO.
That got me to thinking, do I still need to use third party extensions for my SEO? If yes, why? What is it that 3rd party extensions provide that Joomla 2.5's built-in SEO doesn't?
The biggest reason why using an SEO component in all versions of Joomla even 3+ is that Joomla has a habit of creating multiple urls for one page/post meaning that Google finds these as duplicates.
There are just so many reasons why using a SEO extensions for Joomla is better than using the core but here's a few:
I've personally used both and SH404SEF offers the most to be honest but AceSEF has a free version and does the job just fine.